Research On Modeling Of Automobile Body Parts Based On Self-repairing Mechanism

In the highly competitive automobile industry,shortening the development cycle of new product and improving the development efficiency have become a necessity for the survival of enterprises.However,the complex surface model construction of automobile body parts is still a time-consuming manual process.On the one hand,complex design constrains and CAE-based optimization make the surface model in continuous modification process,On the other hand,complex modeling process of automobile parts is difficult to ensure reliability and stability during the design changing and modification.The automobile body surface model is created by complex sequences consisted by a lot of interrelated surface operations.The success of each step operation depends on the quality of the previous step operation,and the quality of the new surface generated by this step operation determines the success of subsequent step operation.Existing modeling mechanisms ignore this quality association,which leads to frequent modeling errors.Thus,this paper aims at actual engineering problems of automobile body and parts design process,and attempts to construct a new modeling mechanism to greatly reduce the manual intervention in the process of automobile body surface modeling,and realize the significant improvement of the overall efficiency through automatic updating.This paper proposed a selfrepairing modeling mechanism that introduces quality checking and repairing mechanism before and after modeling operation steps.Through this kind of protection,this mechanism not only could block the transmission of modeling issue and improve the stability of the modeling process but also reduce manual intervention process and improve the modeling efficiency.This paper takes the modeling issue of “Trapezoidal surface” and “Vertical surface” as research objects,which frequently occur in the modeling process of the automobile body surface model,and applies the self-repairing mechanism to the parametric modeling process,and completes the following works: Firstly,as for different defects(Curve defects,Surface detects,Gap defects,etc.),this mechanism proposes targeted identification and judgment methods,and proposes targeted middle layer geometric repair methods.Secondly,this mechanism constructs a numerical parameters optimization m echanism based on fuzzy evaluation and replaces the tedious manual process,and realizes the automatic repairing process under complex constraints.Finally,this mechanism uses NXOpen API、UFun、Block UI and other interfaces to realize the development and corresponding testing of the software module of the “ The enhanced self-repairing tool of complex automobile body surface modeling process ”.The self-repairing tool abstracts the detection algorithm and repairing method into the knowledge rules in the feature modeling system with the help of knowledge engineering platform,and realizes the automatic management of parameters and data through internal integration,which significantly enhances the stability and robustness of the parametric modeling sequence,when product design parameters are changed,the demand for manual intervention is significantly reduced.The test part set of this study is composed of 15 typical complex automobile body surface models.In the process of program-driven parametric editing,due to the introduction of the new mechanism,the cumulative number of errors in modeling steps has been reduced by 40%,that means reduced nearly 40% of the manual intervention process and verifies the great advantages of self-repairing modeling mechanism.Although this study is based on Siemens NX platform,the geometric problems it targets are indeed universal in automobile body development.Therefore,the ideas and methods of this paper still have the same reference value for surface model design of automobile body parts work on other CAD platforms.